As is well known, various tool holders have been utilized in the prior art which interface with a rotating spindle of a machine tool such as a milling or boring machine to securely hold a cutting tool upon the machine during cutting of a work piece. Though the prior art tool holders are suitable for interfacing a cutting tool to the rotating spindle of the machine tool, these holders possess certain deficiencies which detract from their overall utility.
In most prior art tool holders, a central aperture is formed therein for receiving the shank portion of the cutting tool which is to be interfaced to the milling machine. Typically, the central aperture is formed approximately one to two ten-thousandths of an inch greater in diameter than the shank portion of the cutting tool to allow the shank portion to be easily and quickly inserted thereinto. Thereafter, a set screw extending perpendicular to the cutting tool within the tool holder is tightened upon the cutting tool and the tool holder is drawn or pulled tightly into the spindle so as to rigidly maintain the cutting tool therewithin. However, the formation of the central aperture with a greater diameter than the shank portion of the cutting tool to enable manual reciprocation of the cutting tool within the tool holder has been known to make the tool holder susceptible to non-concentric mounting of the cutting tool therein which in modern, high tolerance machining applications has proved unacceptable. In this regard, in high-speed cutting applications, such as those performed on a vertical milling machine, minor variations in the concentricity of the cutting tool within the tool holder oftentimes causes catastrophic failure in the cutting operation.
A further deficiency associated with many prior art tool holders is the inability of the tool holder to feed coolant fluid onto the cutting portion of the cutting tool during a machining operation. During machining operations, such as those performed on vertical milling machines, coolant fluid is typically applied to the surfaces of the work piece and the cutting portion of the cutting tool to reduce tool wear and to enhance the out by reducing the temperature of the cutting tool and work piece. Additionally, the coolant fluid is used to wash away chips which build up on the work piece during the cutting operation. Since most prior art tool holders are not adapted to allow the passage of coolant fluid therethrough to the surfaces of the cutting tool and work piece, the coolant fluid must generally be applied to the work piece and cutting tool manually or via a separate spray head which is disposed directly adjacent the cutting portion of the cutting tool and work piece.
In recognition of this deficiency, a number of prior art tool holders have been developed which channel coolant fluid through the spindle and onto the cutting tool and work piece. One such tool holder is manufactured by the X-L Tool Company of Moreno Valley, Calif. under the name "Flush Cut." In this particular device, a plurality of angularly oriented fluid passages are disposed in the tool mounting portion of the tool holder so as to spray coolant fluid onto the cutting tool mounted therein. However, the process of forming the angled passages within the tool holder is both expensive and time-consuming. Additionally, the tool holder is not adapted to eliminate eccentricity in the cutting tool when such is mounted therein. Another prior art device which is adapted to apply coolant fluid to the tip of a cutting insert is disclosed in U.S. Pat. No. 4,453,775 to CLEMMOW. However, in the cutting tool disclosed in the CLEMMOW reference, the cutting insert must be provided with a plurality of cross-grooves to allow the coolant fluid to flow over the tip of the cutting insert. Additionally, as with the previously described "FLUSH CUT" tool holder, the cutting tool disclosed in the CLEMMOW reference is not adapted to eliminate eccentricity of the cutting insert relative the tool holder.
The present invention addresses the deficiencies associated with prior art tool holders by providing a tool holder system which is adapted to direct coolant fluid over the cutting tool and is particularly suited to eliminate eccentricity in the mounting of the cutting tool within the tool holder. As such, the present system is specifically adapted to facilitate the rigid and true mounting of a cutting tool within a tool holder for use in high-speed cutting applications.